Laser welding devices, which have a welding energy source and a movable damping device, have been known in practice. The welding energy is set as a function of the workpiece thickness. The value is entered based on the preset parameters. The operator knows the individual plate thickness from the specifications of the components. From this, he calculates the thickness of the plate stack and then sets the welding energy source manually on the basis of predetermined tables. This technique is unsuitable for automation. In addition, it is subject to tolerances and errors.